I went to a local museum's classic motorcycle meet today; saw three CB400F's there, but all earlier than '77. That late model US version really is the ugly bastard child, isn't it? Fugly tank, upright bars and forward pegs... anyway, I wonder if the owner of this one knows what a gold mine he has with those OEM headers in such great shape?

While digging into my fuse block to help with a wiring question, I found this (click to zoom):

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To be honest, I didn't dig further and I'm not sure which "side" of the fuses this little bodge is on, but I know enough about how electricity moves through conductors to know that this isn't cricket! The only reason I can come up with for this is perhaps the clips holding the fuse ends weren't gripping securely, so the wire pulls them tight. Pardon my Français, but really, WTF?!?

Looks like it's been initiated to cope with intermittent connection as you suspect. Wouldn't in itself do anything wrong if on supply side but would increase fuse rating if on outbound terminals.

Thanks K2-K6... your "ifs" got me thinking about that, too, so I removed the fuse block to actually examine which wires on which side of the fuses were shorted. As it turns out, that twisted wire is connecting the black/red and the brown/blue wires. Looking at the UK wiring diagram, I believe this would create a short circuit between the "park" and "headlight" positions of the lighting switch on the right handlebar control, so any position other than "off" would illuminate them all.

But this is a US spec bike, with no light switch, which is wired to have the headlight always on when the ignition switch is on - except when the electric start button is being pressed - at that point the headlight is supposed to go off until the starter button is released. With a short across those two wires, the headlight will always stay on, even when the electric starter is being used, bypassing the protections built into the circuit... such as they are.

... whilst I don’t have the US wiring diagram mattsz, I’m not sure how connecting the Park & HL will bypass the starter button ‘protection’ - ie I’d have thought the ‘protection’ will continue to work as designed? My guess at this bodge is that there’s been a break in the Black/Red feed (to the fuse holder) ... and so the PO has jumped the two together.

Has the PO therefore solved the problem and (lazily) restored the lighting to normal road light functioning? (at the expense of proper Park light function)

... whilst I don’t have the US wiring diagram mattsz, I’m not sure how connecting the Park & HL will bypass the starter button ‘protection’ - ie I’d have thought the ‘protection’ will continue to work as designed?

Perhaps "protection" wasn't the best choice of words - substitute "function?" USA model headlights are always on when the ignition key is on - except when you push the starter button - power to the headlight is then temporarily disconnected until the starter button is released. So the circuit's "function" is to remove the electrical load of the headlight while the starter is used. Whether that's a "protection" could be debated, I suppose. Whatever you call it, with that jumper shorting the two wires in question, the headlight would stay on when the starter button is pressed, which is not the intended design. I think...

My guess at this bodge is that there’s been a break in the Black/Red feed (to the fuse holder) ... and so the PO has jumped the two together.

Has the PO therefore solved the problem and (lazily) restored the lighting to normal road light functioning? (at the expense of proper Park light function)

Thinking about it, I'm liking this idea - you may or may not recall that my starter switch was broken, and it wouldn't operate the starter properly (pic of the switch in this post: http://www.sohc.co.uk/index.php/topic,17599.msg153989.html#msg153989). Full headlight current runs through that switch - the "break in the Black/Red feed (to the fuse holder)" you mentioned could very well have been that broken switch - and I wouldn't have realized it because the headlight was getting power through that bodge...

A soda blaster has many uses, including the parts you are talking about. No media is left, so no issues with little bits if glass or sand being left but, it is a slow process blasting anything with soda. The outcome and time spent is entirely dependant in the output of the compressor you are using. It needs to be a high CFM rating to do an effective job.